Significance To determine the contribution of the somatosensory system to complex primate behaviors such as manual dexterity, bilateral coordination of the hands, multimodal integration, and sensorimotor integration required for goal directed reaching. The evolution of these abilities in humans is firmly intertwined with the evolution of our sensory and motor systems. Thus, in order to understand how these sophisticated behaviors are generated in humans, we must uncover the details of the organization of our sensory systems, and the neural circuitry that subserves complex functions. Objectives The studies are aimed at uncovering the topographic organization of cortical fields, receptive field size, stimulus preference, and detailed topographic connection patterns of fields in LS and PP in monkeys, and at determining if similar fields exist in humans. Results Recently, it has been established that the fMRI technique can be used effectively to determine the topographic organization of fields, and the number of subdivisions within a region of cortex. Thus, in parallel with our electrophysiological and connection studies in monkeys, we will utilize fMRI techniques to explore similar regions of the neocortex in humans. Our stimulus selection and areas of interest will be guided by our results in monkeys. Thus, we will begin with stimulation like that described above, and direct our efforts to areas in the lateral sulcus and posterior parietal cortex. Applying the framework of cortical fields and patterns of connections established in our monkey model to humans, we can expand our stimulus repertoire to include more sophisticated tasks which involve bilateral manipulation, goal directed reaching, and attention. This study represents one of the first efforts to combine different types of techniques in both human and non-human prima tes, and promises to provide a richer understanding of human somatosensory cortex, and its contribution to higher perceptual and cognitive processing. Future Directions Applying the framework of cortical fields and patterns of connections established in our monkey model to humans, we can expand our stimulus repertoire to include more sophisticated tasks which involve bilateral manipulation, goal directed reaching, and attention. This study represents one of the first efforts to combine different types of techniques in both human and non-human primates, and promises to provide a richer understanding of human somatosensory cortex, and its contribution to higher perceptual and cognitive processing. KEY WORDS somatosensory area, neocortex, cognitive processing FUNDING James S. McDonnell Fdn., Grant 98-42 CNS-QUA.05